The present invention relates to a universal pigment preparation for blending with conventional dye and binder systems, and to the production thereof.
Universal pigment preparations are pigment preparations which have good meterability and are used for coloring both aqueous and solventborne paints.
In the production of universal pigment preparations, dispersants or emulsifiers are used, and these physically stabilize the pigment particles in their finely divided form in an aqueous or aqueous/organic medium. For the selection of the dispersants, in addition, compatibility in the various applications is essential. For example, the preparations should be introduced into the application medium easily and without flocculation or reaggregation of the pigment particles.
Since the introduction of water-thinnable basecoats and topcoats, paint manufacturers have had the problem of having to manufacture and stock every shade in the form of the water-thinnable paint and additionally of the solvent-based paint or the precursors in question, in order to be able to accommodate the different equipment used by the user.
It is necessary to use a specific grinding component for production of a suitable pigment paste for every paint system. After production of the pigment paste, one or more further binders in each case are used to complete the paint. These constituents have to be matched to one another in order to obtain a suitable coating medium; for example, it has to be storage-stable and meet the high visual demands. It is possible for grinding to be effected in the main paint binder or for special paste resins (grinding resins) to be used for production of the pigment paste. A general problem is the need to have to create and store a pigment paste for every different paint system for every shade. This makes manufacturing costly and necessitates holding of a large stock.
In the architectural paints segment, for example, universal pigment preparations are used for the coloring of white or transparent base paints. These paints fulfil both a decorative purpose and a protective purpose on buildings. For instance, a universal pigment preparation can be used to color a water-based dispersion wall paint and a solventborne alkyd-based wood paint. It is no longer necessary to go to the lengths of stocking and formulation development of two pigment preparations for the particular intended use. All that is required in hardware stores and specialist dealers is accordingly a dispenser system for blending of a great multitude of shades.
The prior art discloses that, for production of universal pigment preparations, alkylphenol ethoxylates (APEs), specifically octyl- and nonylphenol ethoxylates, are used as dispersing additives in an aqueous medium, since these have a good cost-benefit ratio. Regrettably, it has been found that the degradation products of the APEs are bioaccumulative and act as hormone analogues. For many applications, nonylphenol ethoxylates are therefore already banned. Use in coatings and paints is still legally permitted in Germany, but there is a strong trend in the industry to dispense with these raw materials.
As an alternative to APEs, it is possible to use dispersing additives based on styrene oxide. U.S. Pat. No. 6,552,091 and EP 0 940 406 describe the synthesis of such structures and the use thereof in aqueous universal pigment preparations.
DE10 2011 010580, by contrast, describes the use of oleyl ethoxylates and dispersing additives in aqueous universal pigment preparations. WO 2009/127668 A1 uses a grinding medium rather than a dispersing additive. These grinding media comprise an aqueous formulation composed of a water-thinnable alkyd resin and an acrylate resin. These grinding media can be used for production of aqueous universal pigment pastes.
The disadvantage of the above-described universal pigment preparations/pastes is the use of water. Thus, use in the field of isocyanate-crosslinked polyurethane coatings (2K PU) is not possible. Universal pigment preparations are therefore not used nowadays in the field of industrial paint systems, where the use of 2K PU coatings is standard practice.
WO 2006 097378 describes an aqueous and solventborne pigment preparation composed of a ketone-formaldehyde grinding resin and a styrene oxide-containing dispersant as grinding medium. The solvent used is, for example, butylglycol. It is stated that these pigment preparations can be used both in solventborne and in solvent-free paints. There is no description of use in 2K PU coatings.